Jewish eating habits?

I'm a Christian, but lately I've been noticing some things. First off, why is it that we don't follow the same habits as the Jews? It's the same Law. I don't know anywhere in the Bible where it says "ignore all things prior". So I asked my grandma. She said that we really should follow the law, because it is God's law, we just don't. In church yesterday we read out of the book of Daniel for class, and he refused to eat the king's food. Ten days later, he and the other Jewish boys looked healthier and better nourished than the others who had eaten the king's food did. So, to any Jews out there, I have a question. What exactly are the laws that we have to follow? I did a little research, but it's still kind of unclear. I know pork is off limits, and meat has to be prepared kosher. No birds of prey or scavenger birds. What else is there? And how hard is it to find kosher food in a grocery store? Is growing your own food easier?